I got pulled by the plod on the way home. I was coming down St Martins Lane and, at the junction with Chandos Place, I turned right (Londoners will probably know the junction - it's right next to the Chandos pub). A police van that was coming along the road towards the junction beeped at me and the copper driver wound down his window. The conversation was as follows.
Plod: "Don't you have to obey the law like everyone else?"
Me: "Sorry?"
Plod (pointing to sign): "That sign says 'No Right Turn'"
Me: "Actually, that sign says 'No Entry'. The sign on the other side of the pole says 'No Right Turn'... but the rectangular sign below it says 'Except Cycles'"
Plod: "Oh..." (starting to turn red as his colleague starts to giggle, as do bystanders and the cabbie next to me).
Me (pointing to traffic island I had just crossed): "Another clue might be the clearly marked cycle lane across the traffic island".
Plod: "Sorry..." (winds window up and drives off).
I was tempted to point out that he'd parked his van on the zig-zag lines of a crossing, but I thought that might be too mean.